The 62-year-old veteran test pilot soared into the fringes of space high over California's Mojave desert for the second time in three months, but this time his feat horrified those watching as much as it thrilled them.

His SpaceShipOne, a prototype commercial spaceship about the size of a truck, began corkscrewing wildly through the air just before it left the earth's atmosphere, leaving an ominous spiralled plume of smoke in its wake.

But after dozens of sickening rolls at speeds approaching Mach 3.5, Melvill, who became an astronaut on his first SpaceShipOne space trip in June, managed to wrestle back control of the ship and glided it safely and smoothly back to earth.

As some organisers of the flight and thousands of people watching at the airfield and on US television regained their composure after the spectacular rolls as the craft shot upwards, Melvill said that while he hadn't expected the spin, he had not flinched.

"It was a nice straight trajectory to the top," he said afterwards. "I wish I could say did it on purpose, but it was at no time a worry to me. In fact it was kind of cool," the South African told reporters.

The craft was travelling faster than the speed of a bullet fired from a rifle when windshear, or perhaps a false move by Melvill, set in motion the rolling that lasted for several seconds, he and organisers said.

But the pilot, who was piloting SpaceShipOne at supersonic speeds for the third time and riding it into space for the second said he used the controls to stabilise it and then shut off the engine as he went into sub-orbit.

"It was probably something I did," he said adding however that he could have taken it as high as 360,000 feet (110 kilometers), instead of peaking its trajectory at 337,500 feet (103 kilometers) before it began its descent.

Before gliding back into the desert, Melville said he took snaps of the "black sky" at the edge of space and got a "spectacular" view of his planet too.

Melvill, who would have been retired at 60 if he were an active commercial airline pilot, said he wanted to give the three other pilots in the world's first private space programme a chance to fly the vessel.

"They have trained just as hard as I have and they are younger, have faster reflexes and are better than me in many ways," he said ahead of the next planned flight scheduled for Monday.

But before SpaceShipOne creator and team leader Burt Rutan gives the go ahead for Monday's attempt to win the 10-million-dollar Ansari X Prize, he wants to get to the bottom of how the roll started.

When the rolls began, flight director Doug Shane recommended that Melvill shut off the engines in an attempt to regain control. They were extinguished 11 seconds ahead of their 90-second burning limit.

With the control tower with Shane was Microsoft computer billionaire Paul Allen, the major funder of the SpaceShipOne project, who admitted he was a lot less calm than his team leaders.

"Your heart kind of goes into you throat. Everything seems to be going perfectly and then this rotation develops," said afterwards.

But the experimental pilot with more than 6,900 flying hours under his belt, appeared to experience no such shudders, emerging elated and upbeat from the cockpit.

Before boarding the SpaceCraft, Melvill, who ha flown 134 types of planes and helicopters and has built and tested two of his own aircraft, received a touching good luck charm from his wife.

"She gave me her wedding ring, the dame wedding ring I gave her 43 year ago. I was shocked, she has only taken it off once in those 43 years," he said.

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